Austentic stainless steel and manufacturing method thereof
Abstract
Disclosed are a ultrafine austenitic stainless steel simultaneously satisfying a high strength, a high elongation, and a high yield ratio and a method for manufacturing the same. An austenitic stainless steel according to an embodiment of the present disclosure includes, in percent by weight (wt %), 0.005 to 0.03% of carbon (C), 0.1 to 1.0% of silicon (Si), 0.1 to 2.0% of manganese (Mn), 6.0 to 12.0% of nickel (Ni), 16.0 to 20.0% of chromium (Cr), 0.01 to 0.2% of nitrogen (N), 0.25% or less of niobium (Nb), and the balance of iron (Fe) and inevitable impurities, wherein a thickness central region has an average grain size d of 5 μm or less, and a fraction of a unrecrystallized area in a band form is 10% or less.
Claims
exact text as granted — not AI-modified1 . An austenitic stainless steel comprising, in percent by weight (wt %), 0.005 to 0.03% of carbon (C), 0.1 to 1.0% of silicon (Si), 0.1 to 2.0% of manganese (Mn), 6.0 to 12.0% of nickel (Ni), 16.0 to 20.0% of chromium (Cr), 0.01 to 0.2% of nitrogen (N), 0.25% or less of niobium (Nb), and the balance of iron (Fe) and inevitable impurities,
wherein a thickness central region has an average grain size d of 5 μm or less, and a fraction of a unrecrystallized area in a band form is 10% or less.
2 . The austenitic stainless steel according to claim 1 , wherein a yield strength is at least 700 MPa but not more than 1113 MPa.
3 . The austenitic stainless steel according to claim 1 , wherein an elongation is at least 20% but not more than 41.2%.
4 . The austenitic stainless steel according to claim 1 , wherein a yield ratio is at least 0.8 but not more than 0.96.
5 . A method for manufacturing an austenitic stainless steel, the method comprising:
hot rolling a slab comprising, in percent by weight (wt %), 0.005 to 0.03% of C, 0.1 to 1.0% of Si, 0.1 to 2.0% of Mn, 6.0 to 12.0% of Ni, 16.0 to 20.0% of Cr, 0.01 to 0.2% of N, 0.002 to 0.25% of Nb, and the balance of Fe and inevitable impurities, wherein a thickness central region has an average grain size d of 5 μm or less, and a fraction of a unrecrystallized area in a band form is 10% or less; cold rolling the hot-rolled slab at room temperature with a reduction ratio of 40% or more; and cold annealing a resultant to satisfy a 22 value, represented by Equation (1) below of 0.8 or more:
Ω
=
3.35
-
14.
6
*
[
C
]
+
0
.
1
0
5
*
[
Si
]
+
0.0058
*
[
M
n
]
+
0.032
1
*
[
Cr
]
-
0.22
2
*
[
Ni
]
-
2.02
*
[
N
]
+
0.34
0
*
[
Nb
]
-
0.0053
8
*
Md
30
-
0.0012
4
*
Temp
Equation
(
1
)
(wherein in Equation (1), [C], [Si], [Mn], [Cr], [Ni], [N], and [Nb] represent weight percentages (wt %) of respective elements, Md30 is a value defined by 551-462 ([C]+[N])−9.2*[Si]−8.1*[Mn]−13.7*[Cr]−29 ([Ni]+[Cu])−18.5*[Mo]−68 ([Nb]+[V]), and Temp is a cold annealing temperature (° C.)).
6 . The method according to claim 5 , wherein the cold rolling is performed after the hot rolling without performing hot annealing.Join the waitlist — get patent alerts
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